Electric Soldier Porygon is the most commonly used translation: no known official English title exists for this episode.

(Japanese: でんのうせんしポリゴンComputer Warrior Porygon, commonly Electric Soldier Porygon) is the 38th episode of the Pokémon anime. It was first broadcast in Japan on December 16, 1997. The episode is infamous for resulting in over seven hundred Japanese people (ranging from 3-58 years old[1]) suffering adverse health effects, including epileptic seizures, vomiting, irritated eyes and other related symptoms, due to use of a flashing strobe effect upon its first and only airing. Because of that, this episode was never commercially released or re-broadcast anywhere in the world, and the show went on hiatus for four months.

The frames which caused the seizures are a four-second section in which Pikachu uses an Electric attack on a group of vaccine missiles. The explosion—which occupies a significant portion of the frame—flashes brightly and alternates rapidly between red and blue. The seizures caused by this episode resulted in OLM dropping strobe effects from Pikachu's electric attacks. For years following the incident, a disclaimer was broadcast at the beginning of all Japanese television shows, cautioning viewers not to sit too close to the television screen and to watch only in a brightly-lit room. (「テレビアニメを見るときには、部屋をあかるくして近づきすぎないようにしてみてくださいね。」)

Dr. Akihabara, the inventor of the Pokémon Transport System, is at the Center trying to figure out what went wrong with the system. Brock suggests that a computer virus could be the source of the problem. Akihabara explains that the system couldn't have been infected with a virus because he designed the circuits so well. Ash confuses his explanation of a computer virus with a biological one and thinks the transport system is actually sick. Nurse Joy is told about an anti-virus vaccine, which is a powerful software made to fix the problem. However, upon further investigation into the system, Akihabara unexpectedly gasps and suddenly bolts out of the Center, leaving Joy and the others confused.

Ash, Misty, and Brock break into Akihabara's huge laboratory mansion to figure out what happened to him. Inside, they are startled by a giant holographic image of Akihabara's head. After realizing Akihabara is still friendly, Ash and his friends are lead into a room with a giant machine. The doctor orders them to enter the machine, only telling them that they have entered a giant Human Transporter after he has sealed and locked the door. It is at that time that Porygon appears in the midst of them. Akihabara introduces Porygon to the group and explains that some thieves, namely Team Rocket, have stolen his other prototype Porygon, and are causing havoc. Team Rocket is literally inside the system, blocking the Poké Balls from reaching the Pokémon Centers and keeping them for themselves. Akihabara can't send the anti-virus vaccine in there because humans are inside the computer, and the vaccine would surely blow them to pieces. So, Akihabara's solution is to send Ash and friends into the machine with Porygon to defeat Team Rocket. Ash and his friends refuse, but Akihabara traps them inside the Human Transporter and they are eventually sucked into cyberspace.

The group falls into the Transporter system, but Porygon flies beneath them, grows in size, and catches them. Riding on Porygon's back, Ash, Misty, Brock and Pikachu ride over to Team Rocket's location.

Team Rocket are celebrating their so-far successful raid of Pokémon, confident since they are where no human has ever gone before. Just as Team Rocket claims that no one can catch them, Porygon floats into view, infuriating Meowth. Jessie and James send out Arbok and Weezing into a battle. Weezing uses Poison Gas on them, making Ash and friends cough. Then Porygon regains composure and uses Conversion. Porygon's skin color becomes purple, like Weezing's. Porygon charges, with the group still riding it, right into Weezing and Arbok, effectively knocking them out.

Jessie decides to send their prototype Porygon out next, which looks similar to Akihabara's Porygon, except that it bears a "R" flag on its tail and a zero on its forehead. Jessie's Porygon uses Sharpen to give itself a sword-like beak and tries to attack the other Porygon, who has also changed shape to counter it. Ash and his friends decide to capitalize on the distraction to move the barrier Team Rocket built to hold back all the Poké Balls that were intended to be delivered to the Pokémon Centers. Team's Rocket's attempt to stop them were stopped by Pikachu's Thunder Shock. Then, Akihabara's Porygon sent Team Rocket and the prototype Porygon "blasting off again".

Ash and friends weren't out of the woods yet. Akihabara, represented by a floating TV screen, tells them that trouble is afoot again. Nurse Joy has hired another technician to put the anti-virus vaccine program into the computer, and it indiscriminately targets Team Rocket and Ash and his friends. Trying to fix the problem himself, the doctor did not tell Nurse Joy that the problem was caused by real people and not a virus. As the Vaccine targets the heroes, Porygon gathers Ash and his friends and attempts to escape. From the ground, Team Rocket call Ash out for running away, but are corrected by Ash when he tells them to run from the Vaccine. The Vaccine launches a few rockets that destroy the remainder of the Poké Ball barrier in sparkly, flashing red and blue explosions. Meowth and the prototype Porygon rescue a panicking Jessie and James from the moving sea of Poké Balls and join Akihabara's Porygon in an attempt to escape.

Scene after Pikachu blew up the missile. For health and safety reasons, please click on the image to view the animation.

The vaccine transforms into an object that resembles a flying spaceship, looking like a cross between a Star WarsX-wing and a medical needle, and takes pursuit. It launches more missiles that both of the Porygon dodge with difficulty. Inside the Center, Nurse Joy and the technician are amazed by the resilience of the "virus" and command the Vaccine to unleash a powerful attack. Revealing a gigantic particle gun, it locks onto the prototype Porygon and fires a huge beam, sending Team Rocket downward into a cyberspace bug hole created by the powerful attack. The passengers of Akihabara's Porygon shield their eyes from the blinding red and blue light. The bug holes created by the vaccine's beam cause a system error, and Joy orders the technician not to use the attack again.

Team Rocket awakens at the bottom of one of the bug pits, and realize that their Porygon is knocked out and that they cannot escape. The flying Vaccine locks onto them again, and it seems that it's all over for Team Rocket if it wasn't for a last minute save by Bulbasaur's Vine Whip. Held onto Akihabara's Porygon by Bulbasaur, Team Rocket weighs Porygon down and slows down its progress toward the exit portal. The vaccine locks onto Akihabara's Porygon, and fires four more missiles. Porygon is tired and cannot dodge the missiles. Pikachu steps in and launches a destructive electric attack, detonating two of the missiles in a huge red and blue flashing explosion that covers the entire screen. It buys Porygon just enough time for it to escape through the exit portal as the next two missiles hit the portal itself, destroying Akihabara's entire house, much to Akihabara's dismay, as his Human Transporter is now in pieces.

In the remains of the mansion, Ash and friends are relieved to be back in the real world. Team Rocket spitefully thank Ash for saving them, and then quickly exit, forgetting their prototype Porygon.

The heroes decide to check in on the Pokémon Center. Nurse Joy is relieved to see the Transport system working again, oblivious to the fact that Ash and friends risked their lives to fix the system. In the end, however, Ash, Brock, and Misty decide not to tell Nurse Joy of the ordeal.

Despite Pikachu being the one to launch the seizure-inducing attack, Porygon has never had an important role in another episode since, while Pikachu has appeared in every Pokémon episode and movie to date, barring side story episodes. Porygon's evolved forms, Porygon2 and Porygon-Z, also remained absent from the anime until the fifteenth movie, and even then only appeared in cameo roles. Porygon itself has also made cameo appearances in the first four films and A Chansey Operation. Also, the move Conversion has never been used in the anime since.

Contrary to rumors, neither Blaustein nor Stuart ever stated that 4Kids reduced the speed and intensity of the flashing explosion to make it safe.

The rumor about the existence of an English dub of this episode actually predates Blaustein's word. For example, the first answer Blaustein gave about this episode was a direct response to a user who mentioned reading on Wikipedia about the episode being dubbed: the line "4Kids Entertainment has acually dubbed Computer Soldier Porygon even though it didn't air" was added to the Wikipedia article currently titled Pokémon episodes removed from rotation on March 15, 2006, and Bulbapedia was used as the source.[6]

In fact, when this Bulbapedia article was created on February 27, 2005, it had the line "4 Kids Entertainment have dubbed this episode and reduced the speed and intensity of the flashing explosion to make it safe, but the episode has still never been shown".[7] The line has been without a source until October 28, 2007, when "According to Maddie Blaustein" was added at the beginning of the line.[8]